A Role for the β Isoform of Protein Kinase C in Fear Conditioning

The protein kinase C family of enzymes has been implicated in synaptic plasticity and memory in a wide range of animal species, but to date little information has been available concerning specific roles for individual isoforms of this category of kinases. To investigate the role of the β isoform of PKC in mammalian learning, we characterized mice deficient in the PKCβ gene using anatomical, biochemical, physiological, and behavioral approaches. In our studies we observed that PKCβ was predominantly expressed in the neocortex, in area CA1 of the hippocampus, and in the basolateral nucleus of the amygdala. Mice deficient in PKCβ showed normal brain anatomy and normal hippocampal synaptic transmission, paired pulse facilitation, and long-term potentiation and normal sensory and motor responses. The PKCβ knock-out animals exhibited a loss of learning, however; they suffered deficits in both cued and contextual fear conditioning. The PKC expression pattern and behavioral phenotype in the PKCβ knock-out animals indicate a critical role for the β isoform of PKC in learning-related signal transduction mechanisms, potentially in the basolateral nucleus of the amygdala.